This invention relates to methods and systems for detecting a resistive force applied against an automotive power window due to an object caught in the path of the automotive window.
Many of the automotive vehicles today have electronically controlled closures such as windows and perhaps sun/moon roofs. For purposes of this application all of these closures will be referred to as windows. These systems provide the operator with ease in opening and closing the windows. However, if the operator is distracted while closing the window, it is possible for an object, such as an arm, hand or finger, to be caught between the window and the window frame of the automotive window.
A power window system consists of a regulator coupled to the window and driven by an electric drive motor. One standard motor comprises an output shaft connected to a worm associated with a gear wheel. The gear wheel is connected to an output member coupled to the regulator. As the motor rotates, the worm rotates, causing the gear wheel to also rotate. Rotation of the gear wheel results in the regulator being driven upward and downward.
One such system is disclosed in copending application entitled, xe2x80x9cMethod And System For Detecting An Object Caught In The Path Of An Automotive Window Using A Piezoelectric Torque Sensing Device,xe2x80x9d having Ser. No. 09/391,298 and filed Sep. 9, 1999.
One technique for sensing/detecting the presence of an object caught between a window and its frame when the window is closed utilizes an elastically deformable damper permits angular displacement between the wheel and the output member in response to a resistive torque being applied to the output member. The angular displacement is then sensed using a pair of angular position encoders, wherein one encoder is associated with the gear wheel and the other encoder is associated with the output member. If an object is present, a resistive torque is applied to the output member causing the damper to deform and generating an angular displacement between the output member and the gear wheel. This technique, however, has several challenging technical issues concerning the dampers. As examples, for the system to provide accurate feedback the elastic compliance must be linear throughout the entire range of torque, and the elastic compliance must allow angular displacements large enough to be detected by the encoders. The system is also complicated since the elastic stiffness changes as the damper ages.
Thus, there exists a need for a method and system for sensing a torque associated with a resistive force applied to a power window that overcomes the problems mentioned above.
It is an object of the present invention to provide a method and system for sensing a resistive force being applied to a motor shaft of a power window regulator due to an object being caught in the path of the power window.
It is another object of the present invention to sense the resistive force applied to the motor shaft using a piezoelectric sensor.
It is yet another object of the present invention to transmit the detection of the resistive force as sensed by the piezoelectric sensor using a secondary brush coupled to the power window motor.
Still further, it is an object of the present invention to transmit the detection of the resistive force as sensed by the piezoelectric sensor using power line carrier technology.
In carrying out the above objects, and other objects, features and advantages of the present invention, a method is provided for detecting the presence of an object between an automotive window and its respective frame. The method includes opening and closing a window via a regulator driven by an electric drive motor controlled by a control circuit and powered via a power line. The electric drive motor includes a shaft and a gear wheel associated therewith for cooperating with a second gear wheel of an output member coupled to the regulator. The method also includes sensing a resistive torque applied to the regulator and generating a signal having a value proportional to the resistive torque, transmitting the signal to the control circuit via the power line, and processing the signal to determine if an object is caught between the window and its respective frame.
An alternative method is provided for detecting an object in the path of an automotive window. This method includes opening and closing a window via a regulator driven by an electric drive motor controlled by a control circuit. The electric drive motor includes a rotor shaft having a gear wheel associated therewith for cooperating with a second gear wheel of an output member coupled to the regulator. The electric drive motor further includes a secondary brush assembly coupled directly to the control circuit. The method also includes sensing a resistive torque applied to the regulator and generating a signal having a value proportional to the resistive torque, transmitting the signal to the control circuit via the secondary brush assembly, and processing the frequency signal to determine if an object is caught between the window and its respective frame.
Still further, in carrying out the above objects, and other objects, features and advantages of the present invention, a system is provided for carrying out the method steps described above. The system includes an automotive window opening and closing via a regulator driven by an electric drive motor, which receives power from a power supply via a primary brush assembly coupled to a power line. The system also includes a piezoelectric sensor mounted on the drive motor for sensing a resistive torque applied to the regulator and generating a signal having a value indicative of the resistive torque. A connection transmits the signal from the sensor to a control circuit that determines whether or not an object is caught between the window and a frame based on the signal.
These and other features of the present invention can be understood from the following specification and drawings.